The purpose of the proposed research is to define the mutational, recombinational and selective events that shaped the evolution of the beta-ketoadipate pathway in bacteria. Six different bacterial groups employ distinctive inductive mechanisms - differing in both the extent of co-ordinate control and in the metabolites that act as inducers - to control the synthesis of the enzymes of this catabolic sequence. Acinetobacter calcoaceticus and Pseudomonas putida, two of the aforementioned bacterial groups, are being investigated in detail. Transformation and transduction, respectively, are used to determine the organization of strucutral and regulatory genes in the two species. The amino terminal sequence of muconolactone isomerase from the two species is nearly identical, indicating that homologous structural genes are controlled by apparently heterologous regulatory genes. The evolutionary affinities among the isomerase and enzymes catalyzing four other reactions of the pathway will be established by structural comparison. Thus the evolutionary history of the pathway within each organism will be explored. Intergeneric crosses establishing strains with hybrid structural genes and mixed inductive mechanisms will be attempted.